秋季黄海与渤海异戊二烯含量的分布及海-气通量

为深入研究我国近海异戊二烯的生物地球化学过程及气候效应,于2013年11月6—23日(秋季)在黄海、渤海海域设25个采样点采集海水样品,其中在A断面4个采样点采集不同深度海水样品,运用吹扫捕集-气质联用法对海水中c(异戊二烯)进行分析,研究其分布规律及影响因素,并对异戊二烯的海-气通量进行了探讨. 结果表明:①表层海水中c(异戊二烯)的范围为10.76~48.67 pmol/L,平均值为(22.85±10.52)pmol/L,其水平分布呈北高南低的特征；②c(异戊二烯)与ρ(Chla)(Chla为叶绿素a)呈正相关(R=0.643 4,n=25,P<0.000 4),说明浮游植物生物量是影响研究海域内c(异戊二烯)水平分布与变化规律的重要因素；③调查期间c(异戊二烯)在A断面上的垂直分布较为均匀且没有出现明显分层现象；④表层海水中异戊二烯处于过饱和状态,其海-气释放通量范围为6.26~449.81 nmol/(m2·d),平均值为(91.62±109.75)nmol/(m2·d). 研究显示,我国陆架海区可能是全球海洋、大气异戊二烯重要的源,相关的调查研究工作亟需展开. 

Distribution and Sea-Air Flux of Isoprene in the Yellow Sea and the Bohai Sea in Autumn

Abstract: To clearly understand the biogeochemical process of isoprene and its climatic effects in the coastal seas of China, seawater samples in the surface waters (25 stations) at different depths along A transect (four stations) were collected in the Yellow Sea and the Bohai Sea from November 6^th to 23^rd, 2013. The concentrations of isoprene were determined by gas chromatography with mass spectrum detector (GC-MSD) coupled with purge-and-trap system, to study its distribution as well as influencing factors and sea-air flux. The results showed:1) The concentration of isoprene in the surface waters ranged from 10.76 to 48.67 pmol/L, with an average of (22.85 ±10.52) pmol/L, and decreased from the north to the south. 2) A positive correlation was observed between isoprene and Chla (R=0.6434, n=25, P<0.0004), suggesting that phytoplankton biomass might be an important factor in controlling the distribution and variation of isoprene in the study areas. 3) The vertical distribution of isoprene along A transect was relatively uniform and had no obvious stratification during the survey period. 4) The concentration of isoprene in the surface waters was supersaturated relative to the atmosphere in autumn. The sea-air flux varied from 6.26 to 449.81 nmol/(m²·d), with a mean value of (91.62±109.75) nmol/(m²·d). The study shows that the shelf seas of China might be an important source of isoprene to the global ocean and atmosphere, and related research work needs to be carried out.